Coils mounted in rubber

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Woody850

Woody850

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Somewhere I had read that it could be of a benefit having the coils mounted in rubber.
Could somebody tell me what exactly the reason was and if it helps with a Boyer Mk. III.
Another problem I have noticed is that the coils have been done up pretty tight causing them to bulge where the support clamp comes together, can this cause them to become hot or simply begin to break down.
I have experimented with a piece of bycicle tubing which fits perfectly over the coil and longer bolts for the clamp and am thinking of moving the reflector slightly further forward to make more room for the coils.

What do you think?
 
Woody850 said:
Another problem I have noticed is that the coils have been done up pretty tight causing them to bulge where the support clamp comes together, can this cause them to become hot or simply begin to break down.
Click to expand...

If the coil casing is crushed by overtightening of the clamp then the windings can short to the coil case and the clamp, hence the reason for the rubber insulator between the coil case and clamp.
 
L.A.B. said:
If the coil casing is crushed by overtightening of the clamp then the windings can short to the coil case and the clamp, hence the reason for the rubber insulator between the coil case and clamp.
Click to expand...
Your torque value for the coils is very low. Adhere to it , or risk crushing the aluminum bodies to the inner windings.
 
Many thanks to both of you, these are the things which keep cropping up during the rebuild of this bike all those years of hamfistedness take their toll somewhere.
 
When I got my ‘72 , both coils had been over tightened ( unseen) , after exploring every other possible cause for the miss that happened once warm, I got a new pair of coils , and smooth running , just like that …. never tried the rubber mounting just followed factory torque spec …. all good
 
Woody850 said:
I have experimented with a piece of bycicle tubing which fits perfectly over the coil and longer bolts for the clamp and am thinking of moving the reflector slightly further forward to make more room for the coils.
Click to expand...
If the objective is protection against crushing, you need a thicker layer of rubber than a bicycle tubing due to limited compressibility of the latter. Pressure load will mostly distribute right through the layer and act on the coils as before. I'd try a rubber casing of at least 5mm thickness. Clamp should be of the "closed" non-perforated type. On the other hand, if you aim at increasing adhesion, the bicycle tubing may work all right.

- Knut
 
Tighten them per spec and they will be tight enough to not fall off but not so tight so as to to damage them. :)
 
Tornado said:
Any concern for over heating of coils if wrapped in rubber?
Click to expand...
What I have done is to pull the tubing over them and use longer bolts which can be locked with nylon locking nuts as 10 in/lbs seems very loose since there is no resistance on the mounting plate.
 
Rubber will keep them nice and warm. Is that what you really want.

They are already mounted in rubber. The cause if vibrations is essentially eliminated with the isolastic's, if that why you want them rubber mounted.

As some have mentioned above, you do the bolts up around the coils to just snug them. After all, we are not dumb shits are we. Sorry, I know of idiots who wind the shit out of everything they touch..
 
Inserting rubber between the coil bodies and the clamps is often done to prevent the coil windings from shorting to 'ground' if the casing has been crushed by overtightening, not to isolate them from vibration.
 
L.A.B. said:
Inserting rubber between the coil bodies and the clamps is often done to prevent the coil windings from shorting to 'ground' if the casing has been crushed by overtightening, not to isolate them from vibration.
Click to expand...
Thanks L.A.B. they look a bit iffy that my reason to do it but I have new ones coming today and I will forget the rubber.
Pity they couldn't have done them like the T140v but I guess where.
 
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